The MacApper weblog has a detailed post on how you can use Lifehacker-favorite Quicksilver to control iTunes.

I touched on controlling iTunes with Quicksilver previously in my advanced Quicksilver guide, but this post covers more of the nitty gritty necessary to install the iTunes plug-in and configure powerful triggers (it's also a good general tutorial for using Quicksilver triggers). After the jump, check out my video demonstrating how I control iTunes with Quicksilver.

As you can see, Quicksilver combined with iTunes packs a pretty powerful punch. If you want to get good with Quicksilver, check out my series of Quicksilver guides designed to take you from beginner to advanced Quicksilver usage. — Adam Pash